Memory and metamemory of word-pair learning : an electrophysiological investigation

This dissertation investigates two factors related to human learning and memory processes. The first factor is the testing effect: in comparison to repeatedly study learnt materials, repeated testing is known to be beneficial for future remembering. According to the episodic context account of the testing effect, this beneficial effect of testing is related to a process which reinstates the previously learnt episodic information. The second factor is the delayed judgment of learning (JOL) effect: the metacognitive judgment is more accurate in predicting later remembering when there is a temporal delay between the learning and the judgment than without. Following the cue-utilization account, the delayed JOL is based on the accessibility of the learnt materials whilst the immediate JOL is based on item-characteristics. It is hypothesized that there is a similar retrieval process engaged during testing and/ or during a delayed JOL which enhances the memory performance or the prediction of its accuracy. The neural correlates of testing and JOLs were examined using the electrophysiological method. In the current study, word-pair learning was used as an example of learning and memory: Swahili-German word pairs in the testing experiment (Chapter 2) and German-German semantically-related word pairs in the JOL experiment (Chapter 3). The results showed that the event-related potential (ERP) of the immediate retrieval at testing resembles the ones of the subsequent remembering. However, the ERP of the delayed JOL did not show a similar pattern. In summary, the current data did not support the hypothesis that the similar mechanisms underlie the testing and the delayed JOL effects.Diese Dissertation befasst sich mit zwei Faktoren, die mit Lernen und Gedächtnis des Menschen zusammenhängen. Der erste Faktor ist der Testeffekt: im Vergleich zum wiederholten Lernen von zuvor gelerntem Material wirkt sich wiederholtes Testen förderlich auf das künftige Erinnern aus. Nach dem Episodic-Context-Ansatz zum Testeffekt hängt diese förderliche Wirkung des Testens mit einem Prozess zusammen, der die zuvor gelernte episodische Information wiederherstellt. Der zweite Faktor ist das verzögerte Judgment-of-Learning-Urteil (JOL): metakognitive Urteile sagen künftiges Erinnern akkurater vorher, wenn es eine zeitliche Verzögerung zwischen Lernen und Urteil gibt. Dem Cue-Utilization-Ansatz zufolge basieren verzögerte JOL auf der Zugänglichkeit des gelernten Materials, wohingegen sofortige JOL auf Item-Eigenschaften beruhen. Es wird vermutet, dass ein ähnlicher Abrufmechanismus beim Testen und/ oder bei verzögerten JOL beteiligt ist, der die Erinnerungsleistung oder die Vorhersage ihrer Genauigkeit verstärkt. Die neuronalen Korrelate des Testens und der JOL wurden mit elektrophysiologischen Methoden untersucht. In dieser Arbeit wurde das Lernen von Wortpaaren exemplarisch für Lernen und Gedächtnis verwendet: Swahili-Deutsch-Wortpaare im Experiment zum Testeffekt (Kapitel 2) und semantisch relatierte deutsche Wortpaare im JOL-Experiment (Kapitel 3). Die Ergebnisse zeigen, dass das ereigniskorrelierte Potential (EKP) des sofortigen Abrufs beim Test denen des nachfolgenden Erinnerns ähneln. Allerdings zeigten die EKPs für verzögerte JOL kein vergleichbares Muster. Zusammenfassend kann man sagen, dass die aktuellen Daten die Hypothese, dass dem Testen und den verzögerten JOL ähnliche Mechanismen zugrundeliegen, nicht stützen

Quantum squeezing induced quantum entanglement and EPR steering in coupled optomechanical system

We propose a theoretical project in which quantum squeezing induces quantum entanglement and Einstein-Podolsky-Rosen steering in a coupled whispering-gallery-mode optomechanical system. Through pumping the $\chi^{(2)}$-nonlinear resonator with the phase matching condition, the generated squeezed resonator mode and the mechanical mode of the optomechanical resonator can generate strong quantum entanglement and EPR steering, where the squeezing of the nonlinear resonator plays the vital role. The transitions from zero entanglement to strong entanglement and one-way steering to two-way steering can be realized by adjusting the system parameters appropriately. The photon-photon entanglement and steering between the two resonators can also be obtained by deducing the amplitude of the driving laser. Our project does not need an extraordinarily squeezed field, and it is convenient to manipulate and provides a novel and flexible avenue for diverse applications in quantum technology dependent on both optomechanical and photon-photon entanglement and steering

Urinary Metabolomics on the Biochemical Profiles in Diet-Induced Hyperlipidemia Rat Using Ultraperformance Liquid Chromatography Coupled with Quadrupole Time-of-Flight SYNAPT High-Definition Mass Spectrometry

Ultraperformance liquid chromatography coupled with quadrupole time-of-flight synapt high-definition mass spectrometry metabolomics was used to characterize the urinary metabolic profiling of diet-induced hyperlipidaemia in a rat model. Analysis was done by orthogonal partial least squares discriminant analysis, correlation analysis, heat map analysis, and KEGG pathways analysis. Potential biomarkers were chosen by S-plot and were identified by accurate mass, isotopic pattern, and MS/MS fragments information. Significant differences in fatty acid, amino acid, nucleoside, and bile acid were observed, indicating the perturbations of fatty acid, amino acid, nucleoside, and bile acid metabolisms in diet-induced hyperlipidaemia rats. This study provides further insight into the metabolic profiling across a wide range of biochemical pathways in response to diet-induced hyperlipidaemia