77 research outputs found
Arbitrarily High Super-Resolving Phase Measurements at Telecommunication Wavelengths
We present two experiments that achieve phase super-resolution at
telecommunication wavelengths. One of the experiments is realized in the space
domain and the other in the time domain. Both experiments show high
visibilities and are performed with standard lasers and single-photon
detectors. The first experiment uses six-photon coincidences, whereas the
latter needs no coincidence measurements, is easy to perform, and achieves, in
principle, arbitrarily high phase super-resolution. Here, we demonstrate a
30-fold increase of the resolution. We stress that neither entanglement nor
joint detection is needed in these experiments, demonstrating that neither is
necessary to achieve phase super-resolution.Comment: 5 pages, 7 figure
“Student selection in dentistry – Influence of spatial and manual abilities on dental skill acquisition in preclinical laboratory courses”
Bisher fehlt in der Literatur eine Antwort auf die Frage, welche Fähigkeiten Studierende in vorklinischen Laborkursen der Zahnmedizin benötigen, um praktische Untersuchungs- und Behandlungsmethoden zu erlernen. Im Anwendungsfeld der Studierendenauswahl ist die Fragestellung für den Einsatz von Verfahren relevant, um die in den praktischen Laborkursen benötigten Fähigkeiten in die Bewerberselektion einzubeziehen. Die Ergebnisse in der zahnmedizinischen Studieneignungsdiagnostik fallen inkonsistent im Hinblick auf die Frage aus, ob räumliches Vorstellungsvermögen als kognitive oder manuelles Geschick als nichtkognitive Fähigkeit ausschlaggebend für das Erlernen zahnmedizinischer Fertigkeiten sind (Spratley, 1990). Vor allem das Fehlen eines theoretischen Modells, in welches die widersprüchlichen Studienergebnisse integriert werden könnten, erweist sich als ein Hindernis im Forschungsprozess.
In der vorliegenden Arbeit wurde Ackermans (1988) Theorie des Fertigkeitserwerbs angewandt, um den Einfluss des räumlichen Vorstellungsvermögens und des manuellen Geschicks auf die Aufgabenleistungen beim Erlernen zahnmedizinischer Fertigkeiten in den vorklinischen Laborkursen zu definieren. Entgegen der Untersuchung von Gray und Deem (2002a; b) wurden die vorklinischen Laborkursaufgaben in der vorliegenden Untersuchung in die Typen konsistent-einfach und inkonsistent-komplex unterteilt und in separate Prädiktionsmodelle als Kriterien eingebunden. Die Datenerhebung erfolgte im Studierendenauswahlverfahren der Zahnmedizin an der Universität Hamburg, um Messverzerrungen zu vermeiden, die beispielsweise vorliegen könnten, falls die Testverfahren nicht mit der Motivation absolviert würden, ein bestmögliches Ergebnis zu erzielen. Die Operationalisierung der räumlichen Fähigkeit und der manuellen als instrumentelles, manuelles Geschick wiesen insgesamt eine akzeptable Güte auf, wie aus den Ergebnissen der konfirmatorischen Faktorenanalyse hervorging. Zur Auswertung der postulierten Beziehungen zwischen den Fähigkeitsarten und der Aufgabenleistung in den vorklinischen Laborkursen wurde das „partial least squares“ Verfahren eingesetzt, dessen Parameterschätzungen komplementär mittels robuster Regressionsanalyse überprüft wurden.
Das instrumentelle, manuelle Geschick besaß konform zu den Erwartungen einen moderaten Einfluss auf die Leistung konsistenter, einfacher Aufgaben beim Erwerb zahnmedizinischer Fertigkeiten in der Vorklinik, zu der die kognitive Fähigkeit entgegen den postulierten Erwartungen keinen (schwachen) Zusammenhang aufwies. Zur Leistung inkonsistenter, komplexer Aufgaben wiesen beide Fähigkeiten wie postuliert einen moderaten Einfluss auf. Die Untersuchungsergebnisse bestätigten räumliches Vorstellungsvermögen und instrumentelles, manuelles Geschick als in den vorklinischen Laborkursen benötigte Fähigkeiten zum Erlernen zahnmedizinischer Fertigkeiten, deren Einfluss in Abhängigkeit der Aufgabentypen konsistent-einfach und inkonsistent-komplex ausfiel. Ackermans (1988) Theorie des Fertigkeitserwerbs stellt ein bewährtes Modell dar, das als theoretisches Fundament in der Studieneignungsdiagnostik der Zahnmedizin eingesetzt werden kann, um die Beziehungen zwischen Fähigkeiten und dem Erlernen von Fertigkeiten zu charakterisieren.
Das quasiexperimentelle Untersuchungsdesign, die Stichprobenbeschaffenheit und die nur bedingt zu akzeptierende Messungsgüte des räumlichen Vorstellungsvermögens stellen Limitationen der vorliegenden Untersuchungsergebnisse dar. Die wechselseitige Beziehung der räumlichen und manuellen Fähigkeiten, der Einfluss der Motivation auf die Aufgabenleistungen beim Erwerb zahnmedizinischer Fertigkeiten in den Laborkursen sowie der Phasenverlauf des Fertigkeitserwerbs in Ackermans (1988) Modell stellen mögliche Fragestellungen nachfolgender Studien dar.Abstract
In literature, an answer to the question, which abilities are needed by students to acquire practical examination and treatment methods in preclinical laboratory courses in dentistry, is still missing. This question is important for the use of tests in the field of student selection to ensure, that in practical laboratory courses required abilities are included in the selection of applicants. In dental study aptitude diagnostic, inconsistent findings are reported to the question, whether spatial thinking as cognitive ability or manual dexterity as noncognitive ability are determining for dental skill acquisition (Spratley, 1990). Especially the lack of a theoretical model, that could be used to integrate contradictory results, proves to be an obstacle in research progress.
In the present thesis, Ackerman’s (1988) theory of skill acquisition was used to identify the influence of spatial thinking and manual dexterity on task performance during dental skill acquisition in preclinical laboratory courses. Different to the research by Gray and Deem (2002a; b), the preclinical laboratory tasks were divided into the categories “consistent-simple” and “inconsistent-complex” in the present study and included in separate prediction models as criteria. The data survey took place during student selection procedure in dentistry of the Universität Hamburg to avoid a measurement bias, e.g. if the abilities tests are not completed with the motivation to achieve the best possible results. The operationalization of spatial ability and manual as instrumental, manual dexterity proved to be of acceptable goodness, shown by confirmatory factor analysis’ results. The partial least squares-method was used for analysis of postulated relationships between the types of abilities and task performance in preclinical laboratory courses; its parameter estimations were complementary controlled through robust regression method.
As expected, the instrumental, manual dexterity showed a moderate influence on performance of consistent, simple tasks during skill acquisition in pre-clinic, but the cognitive ability, contrary to the postulated expectation, had no (weak) relationship to those. In agreement with expectations, both abilities revealed a moderate influence on performance of inconsistent, complex tasks. The present research findings confirmed spatial thinking and instrumental, manual dexterity as required abilities for acquisition of dental skills in preclinical laboratory courses, which are depending on the task categories consistent-simple and inconsistent-complex. Ackerman’s (1988) theory of skill acquisition represented a valid model, which can be used as a theoretical basis in dental study aptitude diagnostics for characterizing the relationships between abilities and skill acquisition.
The quasi experimental design, the sample quality and the measurement quality restrictions of spatial ability are limitations of the present thesis. The recursive relationship of spatial and manual abilities, the influence on task performance at dental skill acquisition in laboratory courses through motivation and the phase progress of skill acquisition in Ackerman’s (1988) model are feasible research questions in further studies
Soziale Welten sri-lankisch-tamilischer Migranten in Deutschland
Seit den 1980er Jahren hat sich in Europa und Nordamerika eine transnational vernetzte Diaspora sri-lankisch-tamilischer Migranten entwickelt. Basierend auf dem Ansatz der Sozialen Welten, der dem Symbolischen Interaktionismus entstammt, wird in dieser Arbeit das lokale wie transnationale Engagement und die Partizipation von Migranten an gemeinsamen Aktivitäten als konstitutiv für die Diaspora verstanden. Als exemplarische Handlungsfelder der tamilischen Diaspora in Deutschland werden hinduistische Tempel, Wochenendschulen und Fußballmannschaften untersucht. In diesen verschmelzen lokales Engagement und Partizipation mit transnationaler Vernetzung und ethnisch geprägter Anknüpfung an eine gemeinsame Herkunftskultur auf vielfältige Weise. Die Arbeit zeigt, dass für die lokale Ausgestaltung dieser sozialen Welten einerseits intra-ethnische nationale und transnationale Verflechtungen und andererseits die Verbindung zu lokalen nicht-tamilischen Akteuren von großer Bedeutung ist. Herausgearbeitet werden Verbindungen und Kontaktzonen zwischen den verschiedenen unterschiedlich strukturierten sozialen Welten, durch die eine ethnisch geprägte Sphäre innerhalb der Lebenswelt tamilischer Migranten in Deutschland hervorgebracht wird
Entanglement quantification through local observable correlations
We present a significantly improved scheme of entanglement detection inspired
by local uncertainty relations for a system consisting of two qubits.
Developing the underlying idea of local uncertainty relations, namely
correlations, we demonstrate that it's possible to define a measure which is
invariant under local unitary transformations and which is based only on local
measurements. It is quite simple to implement experimentally and it allows
entanglement quantification in a certain range for mixed states and exactly for
pure states, without first obtaining full knowledge (e.g. through tomography)
of the state.Comment: 5 pages, 3 figures, revised version with new proof and replaced
figure
Decoding Working-Memory Load During n-Back Task Performance from High Channel NIRS Data
Near-infrared spectroscopy (NIRS) can measure neural activity through blood
oxygenation changes in the brain in a wearable form factor, enabling unique
applications for research in and outside the lab. NIRS has proven capable of
measuring cognitive states such as mental workload, often using machine
learning (ML) based brain-computer interfaces (BCIs). To date, NIRS research
has largely relied on probes with under ten to several hundred channels,
although recently a new class of wearable NIRS devices with thousands of
channels has emerged. This poses unique challenges for ML classification, as
NIRS is typically limited by few training trials which results in severely
under-determined estimation problems. So far, it is not well understood how
such high-resolution data is best leveraged in practical BCIs and whether
state-of-the-art (SotA) or better performance can be achieved. To address these
questions, we propose an ML strategy to classify working-memory load that
relies on spatio-temporal regularization and transfer learning from other
subjects in a combination that has not been used in previous NIRS BCIs. The
approach can be interpreted as an end-to-end generalized linear model and
allows for a high degree of interpretability using channel-level or cortical
imaging approaches. We show that using the proposed methodology, it is possible
to achieve SotA decoding performance with high-resolution NIRS data. We also
replicated several SotA approaches on our dataset of 43 participants wearing a
3198 dual-channel NIRS device while performing the n-Back task and show that
these existing methods struggle in the high-channel regime and are largely
outperformed by the proposed method. Our approach helps establish high-channel
NIRS devices as a viable platform for SotA BCI and opens new applications using
this class of headset while also enabling high-resolution model imaging and
interpretation.Comment: 29 pages, 9 figures. Under revie
Digitalisierte Lehrveranstaltungsevaluation und Feedback - Perspektiven von Lehrenden
Im vorliegenden Beitrag werden die Perspektiven von Lehrenden auf eine Form der digitalisierten Lehrveranstaltungsevaluation vorgestellt, die dialogisches Feedback zwischen Lehrenden und Studierenden erleichtert. Die Datenbasis bilden leitfadengestützte Experteninterviews, die mittels Grounded-Theory-Methodologie ausgewertet wurden. Bei der Analyse der Lehrendenperspektive lassen sich drei Ansätze im Umgang mit digitalisierter Lehrveranstaltungs-evaluation herausarbeiten. Der Ansatz A kommt der klassischen Evaluation am Ende der Lehrveranstaltung am nächsten. In Ansatz B dominiert das Entlastungsmotiv und im Ansatz C tritt noch ein pädagogisches Motiv hinzu, dass das Feedbackgespräch selbst als didaktische Methode sieht
On the efficiency of quantum lithography
Quantum lithography promises, in principle, unlimited feature resolution,
independent of wavelength. However, in the literature at least two different
theoretical descriptions of quantum lithography exist. They differ in to which
extent they predict that the photons retain spatial correlation from generation
to the absorption, and while both predict the same feature size, they differ
vastly in predicting how efficiently a quantum lithographic pattern can be
exposed.
Until recently, essentially all experiments reported have been performed in
such a way that it is difficult to distinguish between the two theoretical
explanations. However, last year an experiment was performed which gives
different outcomes for the two theories. We comment on the experiment and show
that the model that fits the data unfortunately indicates that the trade-off
between resolution and efficiency in quantum lithography is very unfavourable.Comment: 19 pages, extended version including a thorough mathematical
derivatio
Experimental determination of the degree of quantum polarisation of continuous variable states
We demonstrate excitation-manifold resolved polarisation characterisation of
continuous-variable (CV) quantum states. In contrast to traditional
characterisation of polarisation that is based on the Stokes parameters, we
experimentally determine the Stokes vector of each excitation manifold
separately. Only for states with a given photon number does the methods
coincide. For states with an indeterminate photon number, for example Gaussian
states, the employed method gives a richer and more accurate description. We
apply the method both in theory and in experiment to some common states to
demonstrate its advantages.Comment: 5 page
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Decoding Depth of Meditation: Electroencephalography Insights From Expert Vipassana Practitioners.
BACKGROUND: Meditation practices have demonstrated numerous psychological and physiological benefits, but capturing the neural correlates of varying meditative depths remains challenging. In this study, we aimed to decode self-reported time-varying meditative depth in expert practitioners using electroencephalography (EEG). METHODS: Expert Vipassana meditators (n = 34) participated in 2 separate sessions. Participants reported their meditative depth on a personally defined 1 to 5 scale using both traditional probing and a novel spontaneous emergence method. EEG activity and effective connectivity in theta, alpha, and gamma bands were used to predict meditative depth using machine/deep learning, including a novel method that fused source activity and connectivity information. RESULTS: We achieved significant accuracy in decoding self-reported meditative depth across unseen sessions. The spontaneous emergence method yielded improved decoding performance compared with traditional probing and correlated more strongly with postsession outcome measures. Best performance was achieved by a novel machine learning method that fused spatial, spectral, and connectivity information. Conventional EEG channel-level methods and preselected default mode network regions fell short in capturing the complex neural dynamics associated with varying meditation depths. CONCLUSIONS: This study demonstrates the feasibility of decoding personally defined meditative depth using EEG. The findings highlight the complex, multivariate nature of neural activity during meditation and introduce spontaneous emergence as an ecologically valid and less obtrusive experiential sampling method. These results have implications for advancing neurofeedback techniques and enhancing our understanding of meditative practices
Real-time neuroimaging and cognitive monitoring using wearable dry EEG
GoalWe present and evaluate a wearable high-density dry-electrode EEG system and an open-source software framework for online neuroimaging and state classification.MethodsThe system integrates a 64-channel dry EEG form factor with wireless data streaming for online analysis. A real-time software framework is applied, including adaptive artifact rejection, cortical source localization, multivariate effective connectivity inference, data visualization, and cognitive state classification from connectivity features using a constrained logistic regression approach (ProxConn). We evaluate the system identification methods on simulated 64-channel EEG data. Then, we evaluate system performance, using ProxConn and a benchmark ERP method, in classifying response errors in nine subjects using the dry EEG system.ResultsSimulations yielded high accuracy (AUC = 0.97 ± 0.021) for real-time cortical connectivity estimation. Response error classification using cortical effective connectivity [short-time direct-directed transfer function (sdDTF)] was significantly above chance with similar performance (AUC) for cLORETA (0.74 ±0.09) and LCMV (0.72 ±0.08) source localization. Cortical ERP-based classification was equivalent to ProxConn for cLORETA (0.74 ±0.16) but significantly better for LCMV (0.82 ±0.12) .ConclusionWe demonstrated the feasibility for real-time cortical connectivity analysis and cognitive state classification from high-density wearable dry EEG.SignificanceThis paper is the first validated application of these methods to 64-channel dry EEG. This study addresses a need for robust real-time measurement and interpretation of complex brain activity in the dynamic environment of the wearable setting. Such advances can have broad impact in research, medicine, and brain-computer interfaces. The pipelines are made freely available in the open-source SIFT and BCILAB toolboxes
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