Quantum dots embedded within nanowires represent one of the most promising technologies for applications in quantum photonics. Whereas the top-down fabrication of such structures remains a technological challenge, their bottom-up fabrication through self-assembly is a potentially more powerful strategy. However, present approaches often yield quantum dots with large optical linewidths, making reproducibility of their physical properties difficult. We present a versatile quantum-dot-innanowire system that reproducibly self-assembles in core-shell GaAs/AlGaAs nanowires. The quantum dots form at the apex of a GaAs/AlGaAs interface, are highly stable, and can be positioned with nanometre precision relative to the nanowire centre. Unusually, their emission is blue-shifted relative to the lowest energy continuum states of the GaAs core. Large-scale electronic structure calculations show that the origin of the optical transitions lies in quantum confinement due to Al-rich barriers. By emitting in the red and self-assembling on silicon substrates, these quantum dots could therefore become building blocks for solid-state lighting devices and third-generation solar cells. S emiconductor quantum dots have been shown to be excellent building blocks for quantum photonics applications, such as single-photon sources and nano-sensing. Desirable properties of a single-photon emitter include high-fidelity anti-bunching (very small g 2 (t = 0)), narrow emission lines (ideally transform limited to a few microelectronvolt) and high brightness (>1 MHz count rate on standard detector). For simplicity, these properties should be achieved either with electrical injection or non-resonant optical excitation. Desirable properties of a nano-sensor include a high sensitivity to local electric and magnetic fields, with the quantum dot located as close as possible to the target region. A popular realization involves Stranski-Krastanow InGaAs quantum dots embedded in a three-dimensional matrix, which are excellent building blocks for the realization of practical singlephoton sources 1 . However, the photon extraction out of the bulk semiconductor is highly inefficient on account of the large mismatch in refractive indices of GaAs and vacuum. An attractive way forward is to embed the quantum dots in a nanowire 2 . To solve the extraction problem, the nanowire is designed to operate as a single-mode waveguide, a so-called photonic nanowire, with a taper as photon out-coupler 3 . Also, for nano-sensing applications, a quantum dot in a nanowire can be located much closer to the active medium. Top-down fabrication of the photonic waveguide is technologically complex, however. Bottom-up fabrication of the photonic waveguide is very attractive 4-6 , but it is at present challenging to self-assemble quantum dots in the nanowires with narrow linewidths and high yields 7,8 . Nano-sensing applications are at present not highly developed. Other degrees of freedom of the quantum-dot-in-nanowire system that can be usefully exploited are the mechanical modes ...
Titin truncating variants (TTNtv) commonly cause dilated cardiomyopathy (DCM). TTNtv are also encountered in ~1% of the general population where they may be silent, perhaps reflecting allelic factors. To better understand TTNtv we integrated TTN allelic series, cardiac imaging and genomic data in humans and studied rat models with disparate TTNtv. In patients with DCM, TTNtv throughout TTN were significantly associated with DCM. Ribosomal profiling in rat revealed the translational footprint of premature stop codons in Ttn, TTNtv position-independent nonsense-mediated degradation of the mutant allele and a signature of perturbed cardiac metabolism. Heart physiology in rats with TTNtv was unremarkable at baseline but became impaired during cardiac stress. In healthy humans, machine-based analysis of high-resolution cardiac scans showed TTNtv to be associated with eccentric cardiac remodelling. These data show that TTNtv have molecular and physiological effects on the heart across species, with a continuum of expressivity in health and disease.
In this paper we derive a system of differential equations on time scales of the Solow type corresponding to a production function depending on several capitals. A sufficient condition for the exponential stability of the steady-state solution with positive coordinates is proved. The obtained results are applied to the case of the Cobb-Douglas type production function. Mathematics subject classification (2010): 34N05, 26E70, 97E40, 97M10.
Liquid phase exfoliation (LPE) is a commonly-used method to produce 2D nanosheets from a range of layered crystals. However, such nanosheets display broad size and thickness distributions and correlations between area and thickness, issues which limit nanosheet application-potential. To understand the factors controlling the exfoliation process, we have liquid-exfoliated 11 different layered materials, size-selecting each into fractions before using AFM to measure the nanosheet length, width and thickness distributions for each fraction. The resultant data shows a clear power-law scaling of nanosheet area with thickness for each material. We have developed a simple non-equilibrium thermodynamics-based model predicting that the power-law pre-factor is proportional to both the ratios of in-planetearing/out-of-plane-peeling energies and in-plane/out-of-plane moduli. By comparing the experimental data with the modulus ratio calculated from first principles, we find close agreement between experiment and theory. This supports our hypothesis that energy equipartition holds between nanosheet tearing and peeling during sonication-assisted exfoliation.
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