Single-resolution and multiresolution extended-Kalman-filter-based reconstruction approaches to optical refraction tomography

The problem of reconstruction of a refractive-index distribution (RID) in optical refraction tomography (ORT) with optical path-length difference (OPD) data is solved using two adaptive-estimation-based extended-Kalman-filter (EKF) approaches. First, a basic single-resolution EKF (SR-EKF) is applied to a state variable model describing the tomographic process, to estimate the RID of an optically transparent refracting object from noisy OPD data. The initialization of the biases and covariances corresponding to the state and measurement noise is discussed. The state and measurement noise biases and covariances are adaptively estimated. An EKF is then applied to the wavelet-transformed state variable model to yield a wavelet-based multiresolution EKF (MR-EKF) solution approach. To numerically validate the adaptive EKF approaches, we evaluate them with benchmark studies of standard stationary cases, where comparative results with commonly used efficient deterministic approaches can be obtained. Detailed reconstruction studies for the SR-EKF and two versions of the MR-EKF (with Haar and Daubechies-4 wavelets) compare well with those obtained from a typically used variant of the (deterministic) algebraic reconstruction technique, the average correction per projection method, thus establishing the capability of the EKF for ORT. To the best of our knowledge, the present work contains unique reconstruction studies encompassing the use of EKF for ORT in single-resolution and multiresolution formulations, and also in the use of adaptive estimation of the EKF's noise covariances. (C) 2010 Optical Society of America

Hyperfine effects in the nuclear magnetic resonance of paramagnetic molecules

Paramagnetic, or open-shell, systems are often encountered in the context of metalloproteins, and they are also an essential part of molecular magnets. Nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for chemical structure elucidation, but for paramagnetic molecules it is substantially more complicated than in the diamagnetic case. Before the present work, the theory of NMR of paramagnetic molecules was limited to spin-1/2 systems and it did not include relativistic corrections to the hyperfine effects. It also was not systematically expandable. --- The theory was first expanded by including hyperfine contributions up to the fourth power in the fine structure constant α. It was then reformulated and its scope widened to allow any spin state in any spatial symmetry. This involved including zero-field splitting effects. In both stages the theory was implemented into a separate analysis program. The different levels of theory were tested by demonstrative density functional calculations on molecules selected to showcase the relative strength of new NMR shielding terms. The theory was also tested in a joint experimental and computational effort to confirm assignment of 11 B signals. The new terms were found to be significant and comparable with the terms in the earlier levels of theory. The leading-order magnetic-field dependence of shielding in paramagnetic systems was formulated. The theory is now systematically expandable, allowing for higher-order field dependence and relativistic contributions. The prevailing experimental view of pseudocontact shift was found to be significantly incomplete, as it only includes specific geometric dependence, which is not present in most of the new terms introduced here. The computational uncertainty in density functional calculations of the Fermi contact hyperfine constant and zero-field splitting tensor sets a limit for quantitative prediction of paramagnetic shielding for now.

"Verwundete Orte" in Hettches Nox und Pareis Die Schattenboxerin

[EN] Body and space play a determinant role in the formation of societies, according to the social analyst Richard Sennet. His thesis that the configuration of spaces in history, such as that of the cities, is closely linked to the perception of the own body offers a relevant theorethical approach for the analysis of Nox (1995) by Thomas Hettche and Die Schattenboxerin (1999) by Inka Parei. In both novels bodies are perceived conscientiously by the self as a wounded and exhausted “I”, but also as a rebellious and fighting “self”. Both novels offer a concept of the body as an inadequate and wounded space, which is actually a key procedure to successfully face the similarly unstable geographical, social and political context of Germany after the Fall of the Berlin Wall.

Raumfigurationen und Macht in Atemschaukel

[EN] Atemschaukel approaches the falling apart and survival in a historically loaded space, such as a labour camp. This novel offers a relevant research field for the space analysis, focused from the perspective of the Spatial Turn, as not only this theoretical frame but also Herta Müller herself conceive of space as a process, unterstood as a reciprocal interaction with the social practice, thus as a spatial and social construct. The representation of space in Atemschaukel is described in this article as a “swinging movement between boxes and abyss”, where the discourse of Leopold Auberg’s memories oscillates between closed and square spaces, on one hand, and open and giddy spaces, on the other hand. In this oscillating movement it is the open spaces that will most clearly show the process of inner destruction of the subject in such oppressive situations as on labour camps, as well as the permanent damages of deportation.

Ursachen für wechselnde Selektionseigenschaften von Schleppnetzsteerten - Bericht über das EU-Forschungsprogramm VARSEL

Die Hoffnung, daß sich Fischbestände mit Hilfe von technischen Maßnahmen, wie der Festsetzung einer Mindeststeertmaschenöffnung, in Größe und Zusammensetzung regulieren lassen, ist in Kreisen der ischereiadministration und -wissenschaft weit verbreitet. Irritierend wirkt aber die Tatsache, daß von zwei oder mehr unabhängigen Untersuchern selten oder nie identische Ausleseeigenschaften bei der gleichen Maschenöffnung festgestellt werden. Bereits bei der Untersuchung eines einzigen Steerts, hinter dem gleichen Schleppnetz an einem Fangplatz eingesetzt, ergeben sich für die einzelnen Hols erhebliche Unterschiede, die nur durch die mehrfache Wiederholung des gleichen Experiments einigermaßen auszugleichen sind. Das bedingt einen erheblichen Aufwand für Selektionsuntersuchungen, bzw. bedingt die Varianz ihrer Ergebnisse. Während einer Forschungsschiffsreise können selten mehr als zwei oder drei verschiedene Konfigurationen geprüft werden. Für die eigentlich notwendige Wiederholung zu anderer Zeit und an anderem Ort fehlen in der Regel die Mittel.

Elektronische Registrierung von Untersuchungsdaten auf See

Die elektronische Erfassung von auf See gewonnenen Daten direkt bei der Entstehung ist eine wesentliche Voraussetzung zur rationellen Nutzung elektronischer Datenverarbeitungssysteme. Die Online-Erfassung erspart nicht nur den späteren zeitaufwand bei der Übertragung der Daten von handschriftlichen Strichlisten in den Rechner, sondern schließt gleichzeitig dabei u.U. entstehende Fehler aus. Darüberhinaus ermöglicht die direkte Eingabe von gewonnenen Daten eine schnelle vorläufige Sichtung von Ergebnissen und erlaubt dadurch die Anpassung von Untersuchungsprogrammen an die an Ort und Stelle erzielten Resultate.

Ab initio study of anharmonicity in high pressure Cmca-4 metallic hydrogen

Hydrogen is the only atom for which the Schr odinger equation is solvable. Consisting only of a proton and an electron, hydrogen is the lightest element and, nevertheless, is far from being simple. Under ambient conditions, it forms diatomic molecules H2 in gas phase, but di erent temperature and pressures lead to a complex phase diagram, which is not completely known yet. Solid hydrogen was rst documented in 1899 [1] and was found to be isolating. At higher pressures, however, hydrogen can be metallized. In 1935 Wigner and Huntington predicted that the metallization pressure would be 25 GPa [2], where molecules would disociate to form a monoatomic metal, as alkali metals that lie below hydrogen in the periodic table. The prediction of the metallization pressure turned out to be wrong: metallic hydrogen has not been found yet, even under a pressure as high as 320 GPa. Nevertheless, extrapolations based on optical measurements suggest that a metallic phase may be attained at 450 GPa [3]. The interest of material scientist in metallic hydrogen can be attributed, at least to a great extent, to Ashcroft, who in 1968 suggested that such a system could be a hightemperature superconductor [4]. The temperature at which this material would exhibit a transition from a superconducting to a non-superconducting state (Tc) was estimated to be around room temperature. The implications of such a statement are very interesting in the eld of astrophysics: in planets that contain a big quantity of hydrogen and whose temperature is below Tc, superconducting hydrogen may be found, specially at the center, where the gravitational pressure is high. This might be the case of Jupiter, whose proportion of hydrogen is about 90%. There are also speculations suggesting that the high magnetic eld of Jupiter is due to persistent currents related to the superconducting phase [5]. Metallization and superconductivity of hydrogen has puzzled scientists for decades, and the community is trying to answer several questions. For instance, what is the structure of hydrogen at very high pressures? Or a more general one: what is the maximum Tc a phonon-mediated superconductor can have [6]? A great experimental e ort has been carried out pursuing metallic hydrogen and trying to answer the questions above; however, the characterization of solid phases of hydrogen is a hard task. Achieving the high pressures needed to get the sought phases requires advanced technologies. Diamond anvil cells (DAC) are commonly used devices. These devices consist of two diamonds with a tip of small area; for this reason, when a force is applied, the pressure exerted is very big. This pressure is uniaxial, but it can be turned into hydrostatic pressure using transmitting media. Nowadays, this method makes it possible to reach pressures higher than 300 GPa, but even at this pressure hydrogen does not show metallic properties. A recently developed technique that is an improvement of DAC can reach pressures as high as 600 GPa [7], so it is a promising step forward in high pressure physics. Another drawback is that the electronic density of the structures is so low that X-ray di raction patterns have low resolution. For these reasons, ab initio studies are an important source of knowledge in this eld, within their limitations. When treating hydrogen, there are many subtleties in the calculations: as the atoms are so light, the ions forming the crystalline lattice have signi cant displacements even when temperatures are very low, and even at T=0 K, due to Heisenberg's uncertainty principle. Thus, the energy corresponding to this zero-point (ZP) motion is signi cant and has to be included in an accurate determination of the most stable phase. This has been done including ZP vibrational energies within the harmonic approximation for a range of pressures and at T=0 K, giving rise to a series of structures that are stable in their respective pressure ranges [8]. Very recently, a treatment of the phases of hydrogen that includes anharmonicity in ZP energies has suggested that relative stability of the phases may change with respect to the calculations within the harmonic approximation [9]. Many of the proposed structures for solid hydrogen have been investigated. Particularly, the Cmca-4 structure, which was found to be the stable one from 385-490 GPa [8], is metallic. Calculations for this structure, within the harmonic approximation for the ionic motion, predict a Tc up to 242 K at 450 GPa [10]. Nonetheless, due to the big ionic displacements, the harmonic approximation may not su ce to describe correctly the system. The aim of this work is to apply a recently developed method to treat anharmonicity, the stochastic self-consistent harmonic approximation (SSCHA) [11], to Cmca-4 metallic hydrogen. This way, we will be able to study the e ects of anharmonicity in the phonon spectrum and to try to understand the changes it may provoque in the value of Tc. The work is structured as follows. First we present the theoretical basis of the calculations: Density Functional Theory (DFT) for the electronic calculations, phonons in the harmonic approximation and the SSCHA. Then we apply these methods to Cmca-4 hydrogen and we discuss the results obtained. In the last chapter we draw some conclusions and propose possible future work.

How Good are Genetic Algorithms at Finding Large Cliques: An Experimental Study

This paper investigates the power of genetic algorithms at solving the MAX-CLIQUE problem. We measure the performance of a standard genetic algorithm on an elementary set of problem instances consisting of embedded cliques in random graphs. We indicate the need for improvement, and introduce a new genetic algorithm, the multi-phase annealed GA, which exhibits superior performance on the same problem set. As we scale up the problem size and test on \hard" benchmark instances, we notice a degraded performance in the algorithm caused by premature convergence to local minima. To alleviate this problem, a sequence of modi cations are implemented ranging from changes in input representation to systematic local search. The most recent version, called union GA, incorporates the features of union cross-over, greedy replacement, and diversity enhancement. It shows a marked speed-up in the number of iterations required to find a given solution, as well as some improvement in the clique size found. We discuss issues related to the SIMD implementation of the genetic algorithms on a Thinking Machines CM-5, which was necessitated by the intrinsically high time complexity (O(n3)) of the serial algorithm for computing one iteration. Our preliminary conclusions are: (1) a genetic algorithm needs to be heavily customized to work "well" for the clique problem; (2) a GA is computationally very expensive, and its use is only recommended if it is known to find larger cliques than other algorithms; (3) although our customization e ort is bringing forth continued improvements, there is no clear evidence, at this time, that a GA will have better success in circumventing local minima.

Der Trainingsraum: Unterrichtsstörung als Bumerang

Anhand eines schulischen Dokumentes zur Methode des Trainingsraums werden Anspruch und Umsetzung der Methode analysiert. Der Trainingsraum verspricht Lehrerinnen und Lehrern eine Methode an die Hand zu geben, um Unterrichtsstörungen erzieherisch in den Griff zu bekommen und vor allem: fortlaufenden Unterricht zu ermöglichen. Das Beispiel zeigt, inwieweit eine Verlagerung des Disziplinierungsproblems in den Trainingsraum doch wieder an den Ort des Geschehens - den Klassenraum - zurückführt. (DIPF/Autor)

Bildungsbericht Dessau-Roßlau 2013

Mit dem vorliegenden kommunalen Bildungsbericht 2013 legt die Stadt Dessau-Roßlau nach 2011 zum zweiten Mal eine Bestandsaufnahme der Bildungslandschaft Dessau-Roßlau vor. Damit ist die Bildungsberichterstattung im Programm „Lernen vor Ort“ zu einem wichtigen Baustein und Planungsinstrument geworden. Der Bildungsbericht ist gleichzeitig eine Einladung an alle Interessierten durch die konstruktive Auseinandersetzung mit den Ergebnissen die nächsten Schritte in eine zukunftsfähige Bildungslandschaft mitzugestalten. (DIPF/Orig.)

A novel GUCY2D mutation, V933A, causes central areolar choroidal dystrophy

Purpose: To identify the genetic cause of central areolar choroidal dystrophy (CACD) in a large Northern Irish family.
Methods: We previously reported linkage of the locus for CACD in this family to an interval of approximately 5 cM on chromosome 17p13 flanked by polymorphic markers D17S1810 and CHLC GATA7B03. We undertook sequence capture, massively-parallel sequencing and computational alignment, base-calling and annotation to identify a causative mutation. Conventional sequencing was used to confirm the results.
Results: Deep sequencing identified a single-base substitution in guanylate cyclase 2D, membrane (retina-specific) (GUCY2D). The novel mutation segregated with the disease phenotype and resulted in substitution of valine by alanine at position 933, within the catalytic domain of the protein. It altered a motif that is strongly conserved in a large number of distantly related proteins across several species, and was predicted to have a damaging effect on protein activity.
Conclusion: Mutations in GUCY2D have previously been associated with dominant cone rod dystrophies (CORD6) and recessive forms of Leber's congenital amaurosis (LCA). This is the first report of GUCY2D mutation causing CACD and adds to our understanding of genotype-phenotype correlation in this heterogeneous group of choroidoretinal dystrophies.

Synchronisation in high-performance integrated circuits

A distribui ção de um sinal relógio, com elevada precisão espacial (baixo skew) e temporal (baixo jitter ), em sistemas sí ncronos de alta velocidade tem-se revelado uma tarefa cada vez mais demorada e complexa devido ao escalonamento da tecnologia. Com a diminuição das dimensões dos dispositivos e a integração crescente de mais funcionalidades nos Circuitos Integrados (CIs), a precisão associada as transições do sinal de relógio tem sido cada vez mais afectada por varia ções de processo, tensão e temperatura. Esta tese aborda o problema da incerteza de rel ogio em CIs de alta velocidade, com o objetivo de determinar os limites do paradigma de desenho sí ncrono. Na prossecu ção deste objectivo principal, esta tese propõe quatro novos modelos de incerteza com âmbitos de aplicação diferentes. O primeiro modelo permite estimar a incerteza introduzida por um inversor est atico CMOS, com base em parâmetros simples e su cientemente gen éricos para que possa ser usado na previsão das limitações temporais de circuitos mais complexos, mesmo na fase inicial do projeto. O segundo modelo, permite estimar a incerteza em repetidores com liga ções RC e assim otimizar o dimensionamento da rede de distribui ção de relógio, com baixo esfor ço computacional. O terceiro modelo permite estimar a acumula ção de incerteza em cascatas de repetidores. Uma vez que este modelo tem em considera ção a correla ção entre fontes de ruí do, e especialmente util para promover t ecnicas de distribui ção de rel ogio e de alimentação que possam minimizar a acumulação de incerteza. O quarto modelo permite estimar a incerteza temporal em sistemas com m ultiplos dom ínios de sincronismo. Este modelo pode ser facilmente incorporado numa ferramenta autom atica para determinar a melhor topologia para uma determinada aplicação ou para avaliar a tolerância do sistema ao ru ído de alimentação. Finalmente, usando os modelos propostos, são discutidas as tendências da precisão de rel ogio. Conclui-se que os limites da precisão do rel ogio são, em ultima an alise, impostos por fontes de varia ção dinâmica que se preveem crescentes na actual l ogica de escalonamento dos dispositivos. Assim sendo, esta tese defende a procura de solu ções em outros ní veis de abstração, que não apenas o ní vel f sico, que possam contribuir para o aumento de desempenho dos CIs e que tenham um menor impacto nos pressupostos do paradigma de desenho sí ncrono.

Evaluation an der FH Bund - Konzepte und Ergebnisse aus den Fachbereichen

Dulisch, Linssen und Reiter (2001) legten ein umfassendes Evaluationskonzept für die FH Bund vor. In den zehn Fachbereichen und im Zentralbereich der FH Bund erfolgt/e eine Diskussion, Modifikation und konkrete Anpassung an die Belange vor Ort. Dieser Prozess wurde in einer Evaluationtagung an der FH Bund im Juni 2003 gebündelt. Die Tagung zeigte, dass alle Fachbereiche und der Zentralbereich Fortschritte machen, wenn auch in unterschiedlichem Tempo. Dieser Band dokumentiert den Status Quo der Evaluation in den Fachbereichen und dem Zentralbereich und folgt damit § 6 Hochschulrahmengesetz (HRG), wonach die Arbeit der Hochschulen bewertet und das Ergebnis der Bewertung veröffentlicht werden soll. Inhaltsübersicht: - Evaluation an Fachhochschulen - Überblick - Empfehlungen des Benchmarking Clubs - Evaluationstagung der FH Bund 2003 - Zentralbereich - Allgemeine und Innere Verwaltung - Arbeitsverwaltung - Auswärtige Angelegenheiten - Bundesgrenzschutz - Bundeswehrverwaltung - Finanzen - Landwirtschaftliche Sozialversicherung - Öffentliche Sicherheit - Gesamtkonzept - Öffentliche Sicherheit - Abteilung Kriminalpolizei - Sozialversicherung - Wetterdienst

Drucktrennen sprödharter Werkstoffe

Drucktrennen ist ein Verfahren zum spanlosen Trennen zylindrischer oder prismatischer Bauteile durch in einem Teilbereich der Mantelfläche auf das Werkstück wirkenden Fluidhochdruck. In der vorliegenden Arbeit werden die Wirkzusammenhänge zwischen der Bearbeitung sprödharter zylindrischer Werkstücke und den resultierenden Oberflächen- und Randzoneneigenschaften theoretisch analysiert und die Ergebnisse mit denen experimenteller Untersuchungen verglichen. Der Fluidhochdruck bewirkt einen hauptsächlich von der Werkstückgeometrie und dem Aufbau der für die Versuchsdurchführung entwickelten Trennkammer abhängigen Spannungszustand des Werkstücks. Gleichzeitig dringt das Trennmedium in Oberflächenanrisse ein und ruft dort lokale Zugspannungen im Bereich der Rißspitze hervor. Erreicht der Fluiddruck einen vom Spannungszustand und der Rißlänge abhängigen kritischen Wert, so wird die Bruchzähigkeit des Werkstoffs überschritten und ein Sprödbruch des Werkstücks ausgelöst. Durch gezielt eingebrachte Kerben kann der Ort der Trennung exakt vorgegeben werden. Die Werkstücktrennung erfolgt senkrecht zur Richtung der größten Hauptspannung, welche stets ungefähr parallel zur Werkstückmittelachse orientiert ist. Um eine völlig ebene Bruchfläche zu erreichen, muß eine Ankerbung in Kammermitte erfolgen und das Werkstück absolut symmetrisch zur Trennfläche ausgerichtet sein. Der vom nachdrängenden Fluid vorangetriebene Bruch wird durch Druckspannungen in bestimmten Bereichen des belasteten Bauteils gehemmt. Die Bruchgeschwindigkeit ist demzufolge in der Regel so niedrig, daß für amorphe und einkristalline Werkstoffe keine Bruchverzweigung erfolgt. Dadurch ist beispielsweise für optisches Glas und einkristallines Silizium die Herstellung spiegelglatter Oberflächen möglich. Die Trennflächen vielkristalliner Werkstoffe weisen dagegen eine geringe Oberflächengüte auf, da der Energieüberschuß im Bereich der Rißspitze nicht ausreicht, um einen transkristallinen Sprödbruch voranzutreiben, sondern stets erhebliche interkristalline Bruchanteile vorliegen.

Makerspace in der Stadtbibliothek Göttingen : Machbarkeitsstudie und Risikoanalyse

Bei dem Konzept Makerspace handelt es sich um ein niedrigschwelliges Angebot, das für alle Besucher Anreize, Ideen und Unterstützung bieten kann. Durch den Faktor des gemeinsamen Lernens werden soziale Grenzen überbrückt und neue Netzwerke gebildet, implizites Wissen wird ausgetauscht und Lernen neu erfahren. Der Makerspace bietet eine Bühne, um eigene Erfahrungen auszutauschen, Wissen an Interessierte weiterzugeben oder gemeinschaftlich an einem kreativen Projekt zu arbeiten. Als Ort des Lernens und der Information, aber auch als Treffpunkt bieten öffentliche Bibliotheken einen idealen Rahmen für ein entsprechendes Angebot. Das modulare Makerspace-Konzept ermöglicht ihnen, die Angebote ganz nach ihren Bedürfnissen und Ansprüchen auszurichten. Vorhandene Medienbestände können in die Makerspace-Aktivitäten eingebunden werden. Makerspaces sind vielversprechende Zukunftsmodelle kollektiver Erfahrungsräume und bieten Platz für eine inklusive Lernwerkstatt für die Gemeinschaft. Aufgrund der vorliegenden Analyse empfiehlt das Projektteam für die Stadtbibliothek Göttingen mit dem Koffermodul zu starten, um die Teilnehmer und Mitarbeiter nicht zu überfordern. Die räumlichen Gegebenheiten lassen aber in einem späteren Stadium auch die Module Schrank und Raum zu. Diese Erweiterungen sollten von der Nutzung und der Nachfrage abhängig gemacht werden.