1,079 research outputs found
Within- and between-subject consistency of perceptual segmentation in periodic noise: A combined behavioral tapping and EEG study
The human auditory system is capable of learning unstructured acoustic patterns that occur repeatedly. While most previous studies on perceptual learning focused on seamless pattern repetitions, our study included several presentation formats, which are more typical for memory tasks (involving temporal delays or irrelevant information between pattern presentations), and probed active recognition of learned patterns more directly. We adapted an established implicit learning paradigm and presented three groups of listeners with the same acoustic patterns in different presentation formats, i.e., either back-to-back, separated by a silent interval or by a masker sound. Participants additionally completed an unexpected memory test after the learning phase. We found substantial learning in all groups, measured indirectly via the increased sensitivity in a perceptual task for patterns that occurred repeatedly (compared to patterns that occurred only once) and more directly via above-chance recognition performance in the memory test. Pattern learning and recognition were robust across presentation formats. Therefore, we propose that similar mechanisms might underlie memory formation for initially unfamiliar sounds in everyday listening situations. Moreover, memories for unstructured acoustic patterns that were acquired implicitly through perceptual learning enable subsequent active recognition
Perceptual learning and recognition of random acoustic patterns
The human auditory system is capable of learning unstructured acoustic patterns that occur repeatedly. While most previous studies on perceptual learning focused on seamless pattern repetitions, our study included several presentation formats, which are more typical for memory tasks (involving temporal delays or irrelevant information between pattern presentations), and probed active recognition of learned patterns more directly. We adapted an established implicit learning paradigm and presented three groups of listeners with the same acoustic patterns in different presentation formats, i.e., either back-to-back, separated by a silent interval or by a masker sound. Participants additionally completed an unexpected memory test after the learning phase. We found substantial learning in all groups, measured indirectly via the increased sensitivity in a perceptual task for patterns that occurred repeatedly (compared to patterns that occurred only once) and more directly via above-chance recognition performance in the memory test. Pattern learning and recognition were robust across presentation formats. Therefore, we propose that similar mechanisms might underlie memory formation for initially unfamiliar sounds in everyday listening situations. Moreover, memories for unstructured acoustic patterns that were acquired implicitly through perceptual learning enable subsequent active recognition
Grain boundary network evolution in electron-beam powder bed fusion nickel-based superalloy Inconel 738
Additive manufacturing (AM) of alloys has attracted much attention in recent years for making geometrically complex engineering parts owing to its unique benefits, such as high flexibility and low waste. The in-service performance of AM parts is dependent on the microstructures and grain boundary networks formed during AM, which are often significantly different from their wrought counterparts. Characteristics such as grain size and morphology, texture, and the detailed grain boundary network are known to control various mechanical and corrosion properties. Advanced understanding on how AM parameters affect the formation of these microstructural characteristics is hence critical for optimising processing parameters to unlock superior properties. In this study, the difficult-to-weld nickel-based superalloy Inconel 738 was fabricated via electron-beam powder bed fusion (EPBF) following linear and random scanning strategies. Random scanning resulted in finer, less elongated, and crystallographically more random grains compared to the linear strategy. However, both scanning strategies achieve unique high grain structure stability up to 1250 ℃ due to the presence of carbides pinning the grain boundaries. Despite significant difference in texture and morphology, majority of grains terminated on {100} habit planes in both linear and random built samples. The results show potential for controlling grain boundary networks during EPBF by tuning scan strategies
Observation of Precipitation Evolution in Fe-Ni-Mn-Ti-Al Maraging Steel by Atom Probe Tomography
We describe the full decomposition sequence in an Fe-Ni-Mn-Ti-Al maraging steel during isothermal annealing at 550 °C. Following significant pre-precipitation clustering reactions within the supersaturated martensitic solid solution, (Ni,Fe)3Ti and (Ni,Fe)3(Al,Mn) precipitates eventually form after isothermal aging for ~60 seconds. The morphology of the (Ni,Fe)3Ti particles changes gradually during aging from predominantly plate-like to rod-like, and, importantly, Mn and Al were observed to segregate to these precipitate/matrix interfaces. The (Ni,Fe)3(Al,Mn) precipitates occurred at two main locations: uniformly within the matrix and at the periphery of the (Ni,Fe)3Ti particles. We relate this latter mode of precipitation to the Mn-Al segregation
Enhancement of Transition Temperature in FexSe0.5Te0.5 Film via Iron Vacancies
The effects of iron deficiency in FexSe0.5Te0.5 thin films (0.8<x<1) on
superconductivity and electronic properties have been studied. A significant
enhancement of the superconducting transition temperature (TC) up to 21K was
observed in the most Fe deficient film (x=0.8). Based on the observed and
simulated structural variation results, there is a high possibility that Fe
vacancies can be formed in the FexSe0.5Te0.5 films. The enhancement of TC shows
a strong relationship with the lattice strain effect induced by Fe vacancies.
Importantly, the presence of Fe vacancies alters the charge carrier population
by introducing electron charge carriers, with the Fe deficient film showing
more metallic behavior than the defect-free film. Our study provides a means to
enhance the superconductivity and tune the charge carriers via Fe vacancy, with
no reliance on chemical doping.Comment: 15 pages, 4 figure
The genealogy of judgement: towards a deep history of academic freedom
The classical conception of academic freedom associated with Wilhelm von Humboldt and the rise of the modern university has a quite specific cultural foundation that centres on the controversial mental faculty of 'judgement'. This article traces the roots of 'judgement' back to the Protestant Reformation, through its heyday as the signature feature of German idealism, and to its gradual loss of salience as both a philosophical and a psychological concept. This trajectory has been accompanied by a general shrinking in the scope of academic freedom from the promulgation of world-views to the offering of expert opinion
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