A Tutorial on the Expectation-Maximization Algorithm Including Maximum-Likelihood Estimation and EM Training of Probabilistic Context-Free Grammars

The paper gives a brief review of the expectation-maximization algorithm (Dempster 1977) in the comprehensible framework of discrete mathematics. In Section 2, two prominent estimation methods, the relative-frequency estimation and the maximum-likelihood estimation are presented. Section 3 is dedicated to the expectation-maximization algorithm and a simpler variant, the generalized expectation-maximization algorithm. In Section 4, two loaded dice are rolled. A more interesting example is presented in Section 5: The estimation of probabilistic context-free grammars.Comment: Presented at the 15th European Summer School in Logic, Language and Information (ESSLLI 2003). Example 5 extended (and partially corrected

Inducing a Semantically Annotated Lexicon via EM-Based Clustering

We present a technique for automatic induction of slot annotations for subcategorization frames, based on induction of hidden classes in the EM framework of statistical estimation. The models are empirically evalutated by a general decision test. Induction of slot labeling for subcategorization frames is accomplished by a further application of EM, and applied experimentally on frame observations derived from parsing large corpora. We outline an interpretation of the learned representations as theoretical-linguistic decompositional lexical entries.Comment: 8 pages, uses colacl.sty. Proceedings of the 37th Annual Meeting of the ACL, 199

Using a Probabilistic Class-Based Lexicon for Lexical Ambiguity Resolution

This paper presents the use of probabilistic class-based lexica for disambiguation in target-word selection. Our method employs minimal but precise contextual information for disambiguation. That is, only information provided by the target-verb, enriched by the condensed information of a probabilistic class-based lexicon, is used. Induction of classes and fine-tuning to verbal arguments is done in an unsupervised manner by EM-based clustering techniques. The method shows promising results in an evaluation on real-world translations.Comment: 7 pages, uses colacl.st

Alterstrends der Innovationstätigkeit bei Erwerbstätigen

Zwei Entwicklungstrends in der Erwerbsarbeit, nämlich die Verlagerung des klassischen Kostenwettbewerbs zum Wettbewerb um innovative Produkte und die Veränderung der Altersstruktur der Erwerbsbevölkerung aufgrund der demographischen Entwicklung werden kurz erläutert und genutzt, um die Entwicklung der Leistungs- und Innovationsfähigkeit Erwerbstätiger über die Spanne des erwerbsfähigen Alters als Zukunftsaufgabe zu kennzeichnen. In diesem Beitrag werden Alterstrends des Erlebens von Innovationsanforderungen durch Erwerbstätige analysiert sowie Befunde empirischer Studien über die Innovationstätigkeit Erwerbstätiger vorgestellt. Mit zwei Indikatoren Hauptakteur bei realisierten Produkt- und Prozessinnovationen im letzten Kalenderjahr und Beteiligung an realisierten Produkt- und Prozessinnovationen im letzten Kalenderjahr werden für eine Gelegenheitsstichprobe Erwerbstätiger und für eine Stichprobe von Innovatoren Alterstrends der Innovationstätigkeit beschrieben. In beiden Studien wird keine Altersabhängigkeit der Innovationstätigkeit festgestellt. Aber es besteht ein Zusammenhang der Innovationstätigkeit mit der Lernhaltigkeit der Arbeitsaufgabe. Erwerbstätige, die Arbeitsaufgaben mit höheren Lernanforderungen bearbeiten, sind häufiger Innovator.Two developments in working life, namely the shift from classical price competition to competition based on innovation and the change of the age-structure of employees caused by the demographic evolution are explained shortly. The development of innovation abilities during working life will be founded as an important task. This study describes age correlations of innovation demands of employees. In two field studies the number of self realized innovations and the number of contributions to innovation were registered. This was carried out with a non random sample of employees and of innovators. Zero correlations between innovation and age exist in all studies. Clear differences in the innovation activities occur between qualification groups of employees. But correlations exist between characteristics of job task and innovation. Higher learning demands in job tasks are connected with more innovation activities

Системы измерения параметров волнения для подводных аппаратов

Выпускная квалификационная работа 97 с., 18 рис., 21 табл., 21 источник, 4 прил. Цель работы – проверка теоретической возможности регистрации и обработки данных о величине морского волнения на некоторой глубине, создание макета прибора, измеряющего соответствующее волнение, на основе датчика акселерометра. Область применения: система управления для автономного необитаемого подводного аппарата. В процессе исследования проводились: теоретический обзор линеаризованной теории волны, испытания пригодности акселерометра для задачи измерения вертикальной составляющей при волновом движении, проектирование макета, написание программы для микроконтроллера, изготовление печатной платы макета.Final qualifying work 97 p., 18 fig., 21 tab., 21 sources, 4 app. The Purpose is to test the theoretical possibility of registration and processing of data on the magnitude of sea waves at a certain depth, the creation of the layout of the device, which measures the corresponding sea swell, based on the accelerometer sensor. Scope: control system for autonomous underwater vehicle. A theoretical overview of the linearized theory of wave test accelerometer suitability for vertical component measurement tasks with wave motion, layout design, writing programs for the microcontroller and making the printed board layout were carried out while research

Stable magnesium peroxide at high pressure

Rocky planets are thought to comprise compounds of Mg and O as these are among the most abundant elements, but knowledge of their stable phases may be incomplete. MgO is known to be remarkably stable to very high pressure and chemically inert under reduced condition of the Earth's lower mantle. However, in 'icy' gas giants as well as in exoplanets oxygen may be a more abundant constituent (Ref. 1,2). Here, using synchrotron x-ray diffraction in laser-heated diamond anvil cells, we show that MgO and oxygen react at pressures above 94 GPa and T = 2150 K with the formation of the theoretically predicted I4/mcm MgO2 (Ref.3). Raman spectroscopy detects the presence of a peroxide ion (O22-) in the synthesized material as well as in the recovered specimen. Likewise, energy-dispersive x-ray spectroscopy confirms that the recovered sample has higher oxygen content than pure MgO. Our finding suggests that MgO2 may substitute MgO in rocky mantles and rocky planetary cores under highly oxidizing conditions

Chromosomal Gains and Losses in Uveal Melanomas Detected by Comparative Genomic Hybridization

Eleven uveal melanomas were analyzed using comparative genomic hybridization (CGH). The most abundant genetic changes were loss of chromosome 3, overrepresentation of 6p, loss of 6q, and multiplication of 8q. The smallest overrepresented regions on 6p and 8q were 6pterp21 and 8q24qter, respectively. Several additional gains and losses of chromosome segments were repeatedly observed, the most frequent one being loss of 9p (three cases). Monosomy 3 appeared to be a marker for ciliary body involvement. CGH data were compared with the results of chromosome banding. Some alterations, e.g., gains of 6p and losses of 6q, were observed with higher frequencies after CGH, while others, e.g., 9p deletions, were detected only by CGH. The data suggest some similarities of cytogenetic alterations between cutaneous and uveal melanoma. In particular, the 9p deletions are of interest due to recent reports about the location of a putative tumor-suppressor gene for cutaneous malignant melanoma in this region