3,788 research outputs found
Editorial: Understanding developmental dyslexia: linking perceptual and cognitive deficits to reading processes
The problem of causation has proven particularly elusive in the case of developmental dyslexia (DD). The field has been dominated by very general hypotheses, such as the idea that DD is caused by a phonological deficit and/or an impairment of the magnocellular pathway. Results are contrasting and causal unidirectional links have not been persuasively demonstrated. Some studies in the Research Topic (RT) re-examine these general hypotheses from the critical perspective of more selective predictions. Others focus on less general deficit hypotheses and stay closer to reading by investigating specific aspects of the reading process such as orthographic learning ability or the ability to deal with multiple-stimulus displays. Studies benefit from new
research paradigms as well as new information from research areas such as neuroimaging or genetics. Below, we sketch the general questions tackled by these studies
MicroRNAs in age-related diseases
Aging is a complex process that is linked to an increased incidence of major diseases such as cardiovascular and neurodegenerative disease, but also cancer and immune disorders. MicroRNAs (miRNAs) are small non-coding RNAs, which post-transcriptionally control gene expression by inhibiting translation or inducing degradation of targeted mRNAs. MiRNAs target up to hundreds of mRNAs, thereby modulating gene expression patterns. Many miRNAs appear to be dysregulated during cellular senescence, aging and disease. However, only few miRNAs have been so far linked to age-related changes in cellular and organ functions. The present article will discuss these findings, specifically focusing on the cardiovascular and neurological systems
Dielectric screening in two-dimensional insulators: Implications for excitonic and impurity states in graphane
For atomic thin layer insulating materials we provide an exact analytic form
of the two-dimensional screened potential. In contrast to three-dimensional
systems where the macroscopic screening can be described by a static dielectric
constant in 2D systems the macroscopic screening is non local (q-dependent)
showing a logarithmic divergence for small distances and reaching the
unscreened Coulomb potential for large distances. The cross-over of these two
regimes is dictated by 2D layer polarizability that can be easily computed by
standard first-principles techniques. The present results have strong
implications for describing gap-impurity levels and also exciton binding
energies. The simple model derived here captures the main physical effects and
reproduces well, for the case of graphane, the full many-body GW plus
Bethe-Salpeter calculations. As an additional outcome we show that the impurity
hole-doping in graphane leads to strongly localized states, what hampers
applications in electronic devices. In spite of the inefficient and nonlocal
two-dimensional macroscopic screening we demonstrate that a simple
approach is capable to describe the electronic and
transport properties of confined 2D systems.Comment: 17 pages, 3 figure
Control of the TORA System through the IDA-PBC without Explicit Solution of Matching Equations
This paper presents the control of a translational oscillator with a rotational actuator (TORA) system, in full gravity, through the interconnection and damping assignment passivity-based control (IDA-PBC). The sought goal is to control the underactuated TORA system while reducing the complexity in solving the partial differential equations coming out from the so-called matching equations, which arise from the IDA-PBC. The performance of the designed controller is illustrated through numerical simulations
Surface terms on the Nishimori line of the Gaussian Edwards-Anderson model
For the Edwards-Anderson model we find an integral representation for some
surface terms on the Nishimori line. Among the results are expressions for the
surface pressure for free and periodic boundary conditions and the adjacency
pressure, i.e., the difference between the pressure of a box and the sum of the
pressures of adjacent sub-boxes in which the box can been decomposed. We show
that all those terms indeed behave proportionally to the surface size and prove
the existence in the thermodynamic limit of the adjacency pressure.Comment: Final version with minor corrections. To appear in Journal of
Statistical Physic
16x125 Gb/s Quasi-Nyquist DAC-Generated PM-16QAM Transmission Over 3590 km of PSCF
We report on a transmission experiment over high-performance pure silica core fiber (PSCF) of 16 Nyquist wavelength-division-multiplexed (Nyquist-WDM) channels at a symbol rate of 15.625 GBaud, using polarization-multiplexed (PM) 16 symbols quadrature amplitude modulation (16QAM), resulting in a per-channel raw bit rate of 125 Gb/s. The channel spacing is 16 GHz, corresponding to 1.024 times the symbol rate. The interchannel crosstalk penalty is drastically reduced through the confinement of the signal spectrum within a near-Nyquist bandwidth, achieved with digital filtering and digital-to-analog converters (DACs) operating at 1.5 samples/symbol. The optical line is a recirculating loop composed of two spans of high-performance PSCF with erbium-doped fiber amplifiers only. The transmission distance of 3590 km at a target line bit-error rate (BER) of 1.5 10^-2 is achieved at a raw spectral efficiency (SE) of 7.81 b/s/Hz. Assuming a commercial hard forward error correction with 20.5% redundancy, capable of handling the target BER, the net SE is 6.48 b/s/Hz, the highest so far reported for multithousand kilometer transmission of PM-16QAM at ≥ 100 Gb/s per channel. These results demonstrate the feasibility of very high SE DAC-enabled ultra-long-haul quasi-Nyquist-WDM transmission using PM-16QAM with current technologies and manageable digital signal processing complexit
Decision directed carrier phase estimation with a limiter for coherent dense wavelength divison multiplexing systems
Various example embodiments are disclosed. According to one example embodiment, a phase error is estimated in a series of digital symbols of a phase-modulated signal, where the signal is subject to a non-linear phase shift error due to transmission of the signal through an optical fiber. A phase correction of an instant digital symbol that succeeds the series of digital symbols is estimated, where the estimated phase correction is based on the estimated phase errors in the series of digital symbols. The estimated phase correction of the instant digital symbol is limited to a maximum absolute value, and the estimated phase correction is applied to the instant digital symbol of the signal
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