1,354,988 research outputs found
PSYNDEX Tests Review für RD 1-2 - TEST ZUR RECHTSCHREIBDIAGNOSE 1-2
No full textThis is a PSYNDEX Tests Review of RD 1-2 - TEST ZUR RECHTSCHREIBDIAGNOSE 1-2. PSYNDEX Tests Reviews are written in German and describe and evaluate psychological and educational tests used in the German-speaking countries. PSYNDEX Tests is offered by the Leibniz Institute for Psychology as open access documentation.Das ist ein PSYNDEX Tests Review zu RD 1-2 - TEST ZUR RECHTSCHREIBDIAGNOSE 1-2. PSYNDEX Tests Reviews beschreiben und bewerten zentrale psychologische und pädagogische Testverfahren, die in den deutschsprachigen Ländern eingesetzt werden, nach einem standardisierten Raster. PSYNDEX Tests wird durch das Leibniz-Institut für Psychologie als Open Access Dokumentation angeboten.publishedVersio
Elisa Rachel Felix
No full textCollection of studio portraits of entertainers, actors and actresses who performed on the American stage in the mid-1800s.
Photograph of a drawing
Actress
b. Elisa Felix, 1820, France
d. 1858, France, of tuberculosis
Handwritten on verso of image: Rachel
Stamped on verso of image: Published by W. Schaus, 749 Broadway, New York. Photographed by Duebochois & Klauser
PH Coll 75.45
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Hyperfine interaction and spin decoherence in quantum dots
No full textHyperfine interaction is a typical example of a topic in physics, that, due to technological advances, experiences a revival. Originally, hyperfine interaction was studied in atomic physics. In atoms, the interaction between the magnetic moments of the electrons and the nucleus leads to the hyperfine structure. The name hyperfine is historically due to the fact that the energy level splittings in atoms due to spin-orbit interaction were discovered first, and referred to as the atomic fine structure. The further splitting of these levels was then named hyperfine structure and the interaction that gives rise to it hyperfine interaction. In recent years, with the rise of nanotechnology, new structures have been created, one of them being so-called quantum dots. Quantum dots are also called artificial atoms, since, like atoms, they confine electrons to tiny (nanometer-size) regions. As for atoms, there is also hyperfine interaction in quantum dots: the spin of an electron confined to a quantum dot interacts with the lattice nuclei. In contrast to atoms, which have properties that are “given” by nature, the properties of quantum dots can be designed and thus allow to not only study new phenomena, but also open the way for new applications. Quantum computing is one of these applications where quantum dots could play an important role. The basic building block for a quantum computer is a quantum bit (qubit). Like a classical bit a qubit is an ideal two-level system. However, a qubit is a quantum mechanical two-level system instead of a classical one. There are several requirements a quantum-mechanical twolevel system has to fulfill to be a good qubit. The requirement central in this thesis is that the two states of the qubit and their superpositions should be long lived. More precisely it is crucial that coherent superpositions of the two states remain coherent for a long time compared to the manipulation time, i.e., that decoherence (the loss of coherence) is sufficiently slow. One promising candidate for the physical implementation of a qubit is the spin of an electron confined in a quantum dot. In an applied magnetic field the spin component along the field direction forms a natural two-level system. Research in the last few years, parts of which are being presented in this thesis, has shown that the main source of decoherence for spins in quantum dots is the hyperfine interaction with the surrounding nuclei in the host material. Since the wave function of an electron confined to a quantum dot extends over many
sites of the underlying cristal lattice, the electron spin also interacts with many
nuclei, in sharp contrast to an electron spin in an atom, which only interacts
with a single nucleus.
In this thesis we address several aspects of hyperfine interaction and decoherence
in quantum dots. First, we analyze some aspects of the decoherence
that arises from the hyperfine interaction. In the case of driven single-spin
oscillations we show that hyperfine interaction leads to a universal phase shift
and a power-law decay. Both of these effects have been confirmed experimentally.
We also find a universal phase shift and a power-law decay for the case
of two electron spins in a double quantum dot in the subspace with total spin
zero along the quantization axis. The appearance of the these effects both
in single and in double quantum dots is a consequence of the non-Markovian
nature of the nuclear spin bath.
Since the main effect of hyperfine-induced decoherence can be attributed to
the uncertainty in the Overhauser field, the effective magnetic field generated
by the nuclei at the position of the electron, one strategy to reduce decoherence
is to prepare the nuclei in a state with a narrow Overhauser field distribution,
i.e., to narrow the nuclear spin state. We propose a method to measure the
Overhauser field using the dynamics of the electron spins as a probe. More
specifically, we propose to narrow the nuclear spin state by monitoring Rabi
oscillations in a double quantum dot.
Hyperfine interaction not only leads to decoherence of the electron spin
state, it also provides a mechanism for interaction between the nuclei in the
quantum dot. We study the dynamics of the Overhauser field under the mutual
interaction between nuclear spins that is mediated by the electron via the
hyperfine interaction. At high magnetic fields we find an incomplete decay of
the Overhauser field. We further show that the decay of the Overhauser field
can be suppressed by measuring the Overhauser field, a clear manifestation of
the quantum Zeno effect
Th. Klauser. A Short History of the Western Liturgy; an account and some reflections
No full textDalmais Irénée-Henri. Th. Klauser. A Short History of the Western Liturgy; an account and some reflections. In: Revue de l'histoire des religions, tome 179, n°1, 1971. pp. 94-95
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
18F-fluorodeoxyglucose-positron emission tomography: a new explorative perspective
No full text18F-Fluorodeoxyglucose-positron emission tomography (18F-FDG-PET) is a new functional imaging technique available for clinical and experimental use. 18F-FDG-PET studies can be used for screening, localization and follow-up of hypermetabolic processes including malignancies, infections and autoimmune processes. For several years it has been applied in oncological, cardiological and neurological patients, but nowadays an increasing number of studies favours its use in patients with autoimmune diseases including large vessel arteritis. From the experimental view, this technique has even become more important since the introduction of a small PET scanner for the use in animal models. This review focuses on technical aspects, clinical experiences and experimental and future perspectives of 18F-FDG-PET, with a special emphasis on large vessel vasculitis and other autoimmune diseases
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