890 research outputs found
Regulation of Drosophila Brain Wiring by Neuropil Interactions via a Slit-Robo-RPTP Signaling Complex
The axonal wiring molecule Slit and its Round-About (Robo) receptors are conserved regulators of nerve cord patterning. Robo receptors also contribute to wiring brain circuits. Whether molecular mechanisms regulating these signals are modified to fit more complex brain wiring processes is unclear. We investigated the role of Slit and Robo receptors in wiring Drosophila higher-order brain circuits and identified differences in the cellular and molecular mechanisms of Robo/Slit function. First, we find that signaling by Robo receptors in the brain is regulated by the Receptor Protein Tyrosine Phosphatase RPTP69d. RPTP69d increases membrane availability of Robo3 without affecting its phosphorylation state. Second, we detect no midline localization of Slit during brain development. Instead, Slit is enriched in the mushroom body, a neuronal structure covering large areas of the brain. Thus, a divergent molecular mechanism regulates neuronal circuit wiring in the Drosophila brain, partly in response to signals from the mushroom body
Suppression of mid-infrared plasma resonance due to quantum confinement in delta-doped silicon
The classical Drude model provides an accurate description of the plasma
resonance of three-dimensional materials, but only partially explains
two-dimensional systems where quantum mechanical effects dominate such as
P:-layers - atomically thin sheets of phosphorus dopants in silicon
that induce novel electronic properties beyond traditional doping. Previously
it was shown that P:-layers produce a distinct Drude tail feature in
ellipsometry measurements. However, the ellipsometric spectra could not be
properly fit by modeling the -layer as discrete layer of classical
Drude metal. In particular, even for large broadening corresponding to
extremely short relaxation times, a plasma resonance feature was anticipated
but not evident in the experimental data. In this work, we develop a physically
accurate description of this system, which reveals a general approach to
designing thin films with intentionally suppressed plasma resonances. Our model
takes into account the strong charge density confinement and resulting quantum
mechanical description of a P:-layer. We show that the absence of a
plasma resonance feature results from a combination of two factors: i), the
sharply varying charge density profile due to strong confinement in the
direction of growth; and ii), the effective mass and relaxation time anisotropy
due to valley degeneracy. The plasma resonance reappears when the atoms
composing the -layer are allowed to diffuse out from the plane of the
layer, destroying its well-confined two-dimensional character that is critical
to its novel electronic properties
Amblyopia and quality of life: a systematic review
Background/Aims
Amblyopia is a common condition which can affect up to 5% of the general population. The health-related quality of life (HRQoL) implications of amblyopia and/or its treatment have been explored in the literature.
Methods
A systematic literature search was undertaken (16th-30th January 2007) to identify the HRQoL implications of amblyopia and/or its treatment.
Results
A total of 25 papers were included in the literature review. The HRQoL implications of amblyopia related specifically to amblyopia treatment, rather than the condition itself. These included the impact upon family life; social interactions; difficulties undertaking daily activities; and feelings and behaviour. The identified studies adopted a number of methodologies. The study populations included; children with the condition; parents of children with amblyopia; and adults who had undertaken amblyopia treatment as a child. Some studies developed their own measures of HRQoL, and others determined HRQoL through proxy measures.
Conclusions
The reported findings of the HRQoL implications are of importance when considering the management of cases of amblyopia. Further research is required to assess the immediate and long-term effects of amblyopia and/or its treatment upon HRQoL using a more standardised approach
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