Site-controlled InP/GaInP quantum dots emitting single photons in the red spectral range

We report on site-controlled growth of InP/GaInP quantum dots (QDs) on GaAs substrates. The QD nucleation sites are defined by shallow nanoholes etched into a GaInP layer. Optimized growth conditions allow us to realize QD arrays with excellent long range ordering on nanohole periods as large as 1.25 mu m. Single QD lines with an average linewidth of 553 mu eV and best values below 200 mu eV are observed. Photoluminescence spectroscopy reveals excitonic and biexcitonic emission in the wavelength range of about 670 nm (1.85 eV) with an exciton-biexciton splitting of 1.8 meV. Second-order photon-autocorrelation measurements show clear single photon emission with g((2))(0) = 0.13 +/- 0.01. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3690872]</p

Fine motor control improves in older adults after one year of piano lessons ::analysis of individual development and its coupling with cognition and brain structure

Musical training can improve fine motor skills, cognitive abilities and induce macrostructural brain changes. However, it is not clear whether the changes in motor skills occur simultaneously with changes in cognitive and neurophysiological parameters. In this study, 156 healthy, musically naïve, and right-handed older adults were recruited and randomly assigned to a piano training or a music listening group. Before, after six and twelve months participants were scanned using MRI and assessed for fine motor skills, auditory working memory and processing speed. A Bayesian multilevel modeling approach was used to examine behavioral and neurophysiological group differences. The relationships between motor and cognitive and between motor and neurophysiological parameters were determined using latent change score models. Compared to music listening, practicing piano resulted in greater improvement in fine motor skills and probably working memory. Only in the piano group, unimanual fine motor skills and gray matter volume of the contralateral M1 changed together during the 6–12-month period. Additionally, M1 co-developed with ipsilateral putamen and thalamus. Playing piano induced more prevalent coupling between the motor and cognitive domain. However, there is little evidence that fine motor control develops concurrently with cognitive functions. Playing an instrument promotes motor, cognitive and neural development into older age. During the learning process, the consolidation of piano skills appears to take place in sensorimotor networks, enabling musicians to perform untrained motor tasks with higher acuity. Relationships between the development of motor acuity and cognition were bidirectional and can be explained by a common cause as well as by shared resources with compensatory mechanisms

Resonant Tunneling Diodes: Mid-Infrared Sensing at Room Temperature

Resonant tunneling diode photodetectors appear to be promising architectures with a simple design for mid-infrared sensing operations at room temperature. We fabricated resonant tunneling devices with GaInAsSb absorbers that allow operation in the 2–4 μm range with significant electrical responsivity of 0.97 A/W at 2004 nm to optical readout. This paper characterizes the photosensor response contrasting different operational regimes and offering a comprehensive theoretical analysis of the main physical ingredients that rule the sensor functionalities and affect its performance. We demonstrate how the drift, accumulation, and escape efficiencies of photogenerated carriers influence the electrostatic modulation of the sensor’s electrical response and how they allow controlling the device’s sensing abilities.Other UBCNon UBCReviewedFacultyResearche

Evidence of cortical thickness increases in bilateral auditory brain structures following piano learning in older adults

Morphological differences in the auditory brain of musicians compared to nonmusicians are often associated with life-long musical activity. Cross-sectional studies, however, do not allow for any causal inferences, and most experimental studies testing music-driven adaptations investigated children. Although the importance of the age at which musical training begins is widely recognized to impact neuroplasticity, there have been few longitudinal studies examining music-related changes in the brains of older adults. Using magnetic resonance imaging, we measured cortical thickness (CT) of 12 auditory-related regions of interest before and after 6 months of musical instruction in 134 healthy, right-handed, normal-hearing, musically-naive older adults (64–76 years old). Prior to the study, all participants were randomly assigned to either piano training or to a musical culture/music listening group. In five regions—left Heschl's gyrus, left planum polare, bilateral superior temporal sulcus, and right Heschl's sulcus—we found an increase in CT in the piano training group compared with the musical culture group. Furthermore, CT of the right Heschl's gyrus could be identified as a morphological substrate supporting speech in noise perception. The results support the conclusion that playing an instrument is an effective stimulator for cortical plasticity, even in older adults

Improved speech in noise perception in the elderly after 6 months of musical instruction

Understanding speech in background noise poses a challenge in daily communication, which is a particular problem among the elderly. Although musical expertise has often been suggested to be a contributor to speech intelligibility, the associations are mostly correlative. In the present multisite study conducted in Germany and Switzerland, 156 healthy, normal-hearing elderly were randomly assigned to either piano playing or music listening/musical culture groups. The speech reception threshold was assessed using the International Matrix Test before and after a 6 month intervention. Bayesian multilevel modeling revealed an improvement of both groups over time under binaural conditions. Additionally, the speech reception threshold of the piano group decreased during stimuli presentation to the left ear. A right ear improvement only occurred in the German piano group. Furthermore, improvements were predominantly found in women. These findings are discussed in the light of current neuroscientific theories on hemispheric lateralization and biological sex differences. The study indicates a positive transfer from musical training to speech processing, probably supported by the enhancement of auditory processing and improvement of general cognitive functions

Improved speech in noise perception in the elderly after six months of musical instruction

Understanding speech in background noise poses a challenge in daily communication, which is a particular problem among the elderly. Although musical expertise has often been suggested to be a contributor of speech intelligibility, the associations are mostly correlative. In the present multisite study conducted in Germany and Switzerland, 156 healthy, normal-hearing elderly were randomly assigned to either piano playing or physically music listening/musical culture groups. The speech reception threshold was assessed using the International Matrix Test before and after a six months intervention. Bayesian multilevel modeling revealed an improvement of both groups over time under binaural conditions. Additionally, the speech reception threshold of the piano group decreased during stimuli presentation to the left ear. A right ear improvement only occurred in the German piano group. Furthermore, improvements were predominantly found in women. These findings are discussed in the light of current neuroscientific theories on hemispheric lateralization and biological sex differences. The study indicates a positive transfer from musical training to speech processing, probably supported by the enhancement of auditory processing and improvement of general cognitive functions

Six months of piano training in healthy elderly stabilizes white matter microstructure in the fornix, compared to an active control group

While aging is characterized by neurodegeneration, musical training is associated with experience-driven brain plasticity and protection against age-related cognitive decline. However, evidence for the positive effects of musical training mostly comes from cross-sectional studies while randomized controlled trials with larger sample sizes are rare. The current study compares the influence of six months of piano training with music listening/musical culture lessons in 121 musically naïve healthy elderly individuals with regard to white matter properties using fixel-based analysis. Analyses revealed a significant fiber density decline in the music listening/musical culture group (but not in the piano group), after six months, in the fornix, which is a white matter tract that naturally declines with age. In addition, these changes in fiber density positively correlated to episodic memory task performances and the amount of weekly piano training. These findings not only provide further evidence for the involvement of the fornix in episodic memory encoding but also more importantly show that learning to play the piano at an advanced age may stabilize white matter microstructure of the fornix.</p

Music interventions in 132 healthy older adults enhance cerebellar grey matter and auditory working memory, despite general brain atrophy

Normal aging is associated with brain atrophy and cognitive decline. Working memory, involved in cognitive functioning and daily living, is particularly affected. Music training gained momentum in research on brain plasticity and possible transfer effects of interventions on working memory, especially in the context of healthy aging. This longitudinal voxel-based morphometry study evaluated effects of 6-month music interventions on grey matter volume plasticity and auditory working memory performance in 132 healthy older adults. This study is part of a randomized controlled trial comparing two interventions: piano practice (experimental group) and musical culture (musical listening awareness, active control). We report significant grey matter volume increase at whole-brain level in the caudate nucleus, Rolandic operculum and inferior cerebellum when merging both groups, but no group differences. Cerebellar grey matter increase, training intensity metrics and sleep were positively associated with tonal working memory improvement. Digit Span Backward verbal working memory performance also increased. Using region of interest analyses, we showed a group difference in the right primary auditory cortex grey matter volume, decreasing in the musical group while staying stable in the piano group. In contrast, a significant 6-month whole-brain atrophy pattern consistent with longer-term investigations of the aging brain was revealed. We argue that education for seniors should become a major policy priority in the framework of healthy aging, to promote brain plasticity and cognitive reserve, through stimulating group interventions such as music-making and active listening

Increased functional connectivity in the right dorsal auditory stream after a full year of piano training in healthy older adults

Learning to play an instrument at an advanced age may help to counteract or slow down age-related cognitive decline. However, studies investigating the neural underpinnings of these effects are still scarce. One way to investigate the effects of brain plasticity is using resting-state functional connectivity (FC). The current study compared the effects of learning to play the piano (PP) against participating in music listening/musical culture (MC) lessons on FC in 109 healthy older adults. Participants underwent resting-state functional magnetic resonance imaging at three time points: at baseline, and after 6 and 12 months of interventions. Analyses revealed piano training-specific FC changes after 12 months of training. These include FC increase between right Heschl’s gyrus (HG), and other right dorsal auditory stream regions. In addition, PP showed an increased anticorrelation between right HG and dorsal posterior cingulate cortex and FC increase between the right motor hand area and a bilateral network of predominantly motor-related brain regions, which positively correlated with fine motor dexterity improvements. We suggest to interpret those results as increased network efficiency for auditory-motor integration. The fact that functional neuroplasticity can be induced by piano training in healthy older adults opens new pathways to countervail age related decline