3,312 research outputs found
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A physiological marker of recognition memory in adults with autism spectrum disorder? The Pupil Old/New Effect
This study investigated the pupil Old/New effect in individuals with Autism Spectrum Disorder (ASD) and typical development (TD). Participants studied verbal and visual meaningful and meaningless materials in black and white on a computer screen. Pupil sizes were measured while participants performed a Remember (episodic memory with context) /Know (semantic memory, no context) recognition memory test. ASD compared to TD individuals showed significantly reduced recognition rates for all materials. Both groups showed better memory for visual compared to verbal (picture superiority effect) and meaningful compared to meaningless materials. A pupil size ratio (pupil size for test item divided by baseline) for old (studied) and new (unstudied) materials indicated larger pupils for old compared to new materials only for the TD but not the ASD group. Pupil size in response to old versus new items was positively related to recognition accuracy, confirming that the pupil Old/New effect reflects a memory phenomenon in the ASD group. In addition, this study suggests an involvement of the noradrenergic neurotransmitter system in the abnormal hippocampal functioning in ASD. Implications of these findings as well as their underlying neurophysiology will be discussed in relation to current theories of memory in ASD
Start to end simulations of the ERL prototype at Daresbury Laboratory
Daresbury Laboratory is currently building an Energy Recovery Linac Prototype (ERLP) that will serve as a research and development facility for the study of beam dynamics and accelerator technology important to the design and construction of the proposed 4th Generation Light Source (4GLS) project. Two major objectives of the ERLP are the demonstration of energy recovery and of energy recovery from a beam disrupted by an FEL interaction as supplied by an infrared oscillator system. In this paper we present start-to-end simulations of the ERLP including such an FEL interaction. The beam dynamics in the highbrightness injector, which consists of a DC photocathode Gun and a superconducting booster, have been modelled using the particle tracking code ASTRA. After the booster the particles have been tracked with the code elegant. The 3D code GENESIS 1.3 was used to model the FEL interaction with the electron beam at 35 MeV. A brief summary of impedance and wakefield calculations for the whole machine is also given
Long-range electron transfer in structurally engineered pentaammineruthenium (histidine-62) cytochrome c
In many biological processes, long-range electron transfer (ET) plays a key role. When the three-dimensional structures of proteins are accurately known, use of modified proteins and protein-protein complexes provides an experimental approach to study ET rates between two metal centers. For Ru(His)- modified proteins, the introduction of histidine residues at any desired surface location by site-directed mutagenesis opens the way for systematic investigations of ET pathways
Exploratory spectrum calculations using overlap valence quarks on a staggered sea
We present exploratory results for the hadron mass spectrum and pseudoscalar
meson decay constants using mixed actions. We use improved staggered sea quarks
and HYP-smeared overlap valence quarks. We obtain good signals on 10
configurations at one lattice spacing and two different sets of sea quark
masses.Comment: Lattice2004(spectrum), 3pages, 4 figure
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Differential fear conditioning in Asperger's syndrome: Implications for an amygdala theory of autism
Since the first descriptions of individuals with autism spectrum disorders (ASD), abnormalities in socio-emotional behaviours have been described as amongst the most characteristic clinical features of this condition. Current evidence in this area suggests that individuals with ASD experience difficulties in the perception and expression of emotions within the social domain. The causes for these emotional difficulties are, however, still poorly understood. At the developmental level, it is unclear whether emotional disturbances constitute a primary feature of the clinical presentation of ASD or whether they are secondary to abnormalities in other areas of cognition. At the neurobiological level, it is still debated to what extent abnormalities of the limbic system, in particular the amygdala, may be responsible for the emotional disturbances characterising ASD. Here we show that a group of individuals with Asperger's syndrome exhibit a pattern of abnormality in differentially acquiring fear, which suggests that their fear responses are atypically modulated by conditioned and non-conditioned stimuli. On the basis of these results and the existing literature we suggest that ASD may be characterised by atypicalities in the integration of physiological and cognitive aspects of emotional experiences which we argue arise because of poor connectivity between the amygdala and functionally associated cortical areas
Precision measurement of the branching ratio in the 6P3/2 decay of BaII with a single trapped ion
We present a measurement of the branching ratios from the 6P3/2 state of BaII
into all dipoleallowed decay channels (6S1/2, 5D3/2 and 5D5/2). Measurements
were performed on single 138Ba+ ions in a linear Paul trap with a
frequency-doubled mode-locked Ti:Sapphire laser resonant with the 6S1/2->6P3/2
transition at 455 nm by detection of electron shelving into the dark 5D5/2
state. By driving a pi Rabi rotation with a single femtosecond pulse, a
absolute measurement of the branching ratio to 5D5/2 state was performed.
Combined with a measurement of the relative decay rates into 5D3/2 and 5D5/2
states performed with long trains of highly attenuated 455 nm pulses, it
allowed the extraction of the absolute ratios of the other two decays. Relative
strengths normalized to unity are found to be 0.756+/-0.046, 0.0290+/-0.0015
and 0.215+/-0.0064 for 6S1/2, 5D3/2 and 5D5/2 respectively. This approximately
constitutes a threefold improvement over the best previous measurements and is
a sufficient level of precision to compare to calculated values for dipole
matrix elements.Comment: 6 pages, 5 figures, 1 tabl
Extrapolations of Lattice Meson Form Factors
We use chiral perturbation theory to study the extrapolations necessary to
make physical predictions from lattice QCD data for the electromagnetic form
factors of pseudoscalar mesons. We focus on the quark mass, momentum, lattice
spacing, and volume dependence and apply our results to simulations employing
mixed actions of Ginsparg-Wilson valence quarks and staggered sea quarks. To
determine charge radii at quark masses on the lattices currently used, we find
that all extrapolations except the one to infinite volume make significant
contributions to the systematic error.Comment: 14pp, discussion and Ref. added for disconnected diagram
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